System, method and apparatus for providing direct current

ABSTRACT

A system and method for providing direct-current power is described. In one embodiment a direct current voltage is converted into at least two regulated DC voltages, and a first of the at least two regulated DC voltages is applied across a first and second outputs and a second of the at least two regulated DC voltages is applied across the second output and a third output. And when a first impedance across the first and second outputs is less than a second impedance across the second and third outputs, current is received via the second output while delivering power to the first and second impedances.

FIELD OF THE INVENTION

The present invention relates to power supplies. In particular, but notby way of limitation, the present invention relates to systems andmethods for providing regulated direct current.

BACKGROUND OF THE INVENTION

There are currently many systems that operate under direct current (DC)power, and many additional systems that operate under alternatingcurrent (AC) power that may be converted to operate under DC power dueto benefits in cost, voltage regulation tolerances and energyefficiency.

For example, power provided to processing tools for flat-panelprocessing and semiconductor processing may be distributed by DCsystems. In addition, power distribution for data centers (e.g., serverfarms), commercial buildings and military applications may be bestsuited to DC power distribution.

Power, however, is typically distributed by utilities at AC voltagesthat requires high power conversion from AC to DC voltages. Mostcommonly, service entrance voltages provided by utilities are 480, 400,and 380 voltages for North America, Europe and Asia, respectively. Butthe DC voltages that are typically utilized are not easily and/orefficiently derived from these AC voltages. To arrive at a usable DCvoltage, for example, the source AC voltage is typically converted tothe desired DC voltage by stepping the AC voltage down with atransformer prior to rectification or using a two-stage conversionprocess. Both of these solutions, however, are expensive and lossy.Accordingly, a system and method are needed to address the shortfalls ofpresent technology and to provide other new and innovative features.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention that are shown in thedrawings are summarized below. These and other embodiments are morefully described in the Detailed Description section. It is to beunderstood, however, that there is no intention to limit the inventionto the forms described in this Summary of the Invention or in theDetailed Description. One skilled in the art can recognize that thereare numerous modifications, equivalents and alternative constructionsthat fall within the spirit and scope of the invention as expressed inthe claims.

In one exemplary embodiment, the present invention may be characterizedas an apparatus comprising a rectifier configured to rectify analternating-current (AC) voltage so as to generate a firstdirect-current (DC) voltage and a regulator including a first, second,and third outputs, the first and second outputs configured to connect toa first load and the second and third outputs configured to couple to asecond load. The regulator in this embodiment is configured to apply,using the first direct-current voltage, a regulated second DC voltagebetween the first and the second outputs and a regulated third DCvoltage between the second and third outputs, each of the regulatedsecond and third DC voltages having a magnitude that is less than themagnitude of the first DC voltage.

In another embodiment, the invention may be characterized as a methodfor providing direct-current power, the method including converting adirect current voltage into at least two regulated DC voltages, applyinga first of the at least two regulated DC voltages across a first andsecond outputs and a second of the at least two regulated DC voltagesacross the second output and a third output, and receiving, when a firstimpedance across the first and second outputs is less than a secondimpedance across the second and third outputs, current via the secondoutput while delivering power to the first and second impedances.

As previously stated, the above-described embodiments andimplementations are for illustration purposes only. Numerous otherembodiments, implementations, and details of the invention are easilyrecognized by those of skill in the art from the following descriptionsand claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects and advantages and a more complete understanding of thepresent invention are apparent and more readily appreciated by referenceto the following Detailed Description and to the appended claims whentaken in conjunction with the accompanying Drawings wherein:

FIG. 1 is a block diagram depicting an exemplary embodiment of thepresent invention;

FIG. 2 is a block diagram depicting another embodiment of the presentinvention;

FIG. 3 is a schematic diagram of an exemplary embodiment of the splitbus regulator depicted in FIGS. 1 and 2;

FIG. 4 is a schematic diagram of another embodiment of the split busregulator depicted in FIGS. 1 and 2;

FIG. 5 is a schematic diagram of yet another embodiment of the split busregulator depicted in FIGS. 1 and 2;

FIG. 6 is a schematic diagram of yet another embodiment of a split busregulator;

FIG. 7 is a flowchart depicting an exemplary method in accordance withseveral embodiments of the present invention.

DETAILED DESCRIPTION

Referring now to the drawings, where like or similar elements aredesignated with identical reference numerals throughout the severalviews, and referring in particular to FIG. 1, it is a block diagram 100depicting an exemplary embodiment of the present invention. Shown are anAC source voltage 102, a DC power supply 104 that is coupled to both anin input/output (I/O) module 106 and N loads via three outputs 108, 110,112. The DC power supply 104 in this embodiment includes a controlmodule 114 coupled to the I/O module 106, a rectifier 116 and a splitbus regulator 118.

The magnitude of the AC source voltage 102 that is applied to therectifier 116 may vary depending upon the originator of the AC sourcevoltage 102. In North America, power is often distributed at 480 AC, andin Europe power is frequently distributed at 400 AC volts while in Asia380 volts AC is a common distribution voltage. In some embodiments forexample, the AC power source is a 4-wire wye-configured power sourcethat provides 480 volts line-to-line and 277 volts line-to-neutral. Inother embodiments the AC power source is a 3-wire delta-configured powersource that provides 480 volts line-to-line. In yet other embodimentsthe AC power source is a 4-wire wye-configured power source thatprovides 208 volts line-to-line and 120 volts line-to-neutral. And instill other embodiments the AC power source is a 4-wire delta-configuredpower source that provides 240 volts line-to-line and 120 voltsline-to-neutral. The AC power source may also be a single phase sourceincluding a 2-wire 120 volt source or a 3-wire 120 and 240 volt source.

The rectifier 116 in the exemplary embodiment is an active rectifierconfigured to rectify the AC source voltage 102 and provide a regulatedDC voltage 120, also referred to herein as a DC source voltage 120, thatis applied to the split bus regulator 118. In several embodiments the DCsource voltage 120 is produced without the AC source voltage 102 beingstepped down. In some embodiments for example, the rectifier 116 isconfigured to rectify an AC source voltage 102 that is 480 volts AC andapply the DC source voltage 120 to the split bus regulator 118 at arange of voltages in excess of 650 DC volts. In other embodiments therectifier is configured to rectify 480, 400 or 380 Vac and provide theDC source voltage 120 to the split bus regulator 118 at a fixed 760 Vdc.In other embodiments, the DC power supply 104 is configured to receive aDC voltage and need not include the rectifier 116.

In general, the split bus regulator 118 is configured, responsive to theDC source voltage 120, to apply a second regulated DC voltage 122 acrossthe first output 108 and the second output 110 and a third regulated DCvoltage 124 across the second output 110 and the third output 112 of theDC power supply 104. Both the second and third regulated voltages 122,124 are less than the DC source voltage 120. As a consequence, tworeduced and regulated DC voltages are produced without either employinga step-down transformer prior to rectification or a bucking stagefollowing rectification.

As depicted in FIG. 1, the DC power supply 104 in the present embodimentprovides power to N loads with three conductors 126, 128, 130. Inparticular, the second regulated DC voltage 122 is applied to a firstset of loads 132 with a first outer conductor 126 and a center conductor128, and the third regulated DC voltage 124 is applied to a second setof loads 134 with the center conductor 128 and a second outer conductor130.

In some embodiments, split bus regulator 118 is configured so that thesecond regulated DC voltage 122 and the third regulated DC voltage 124have substantially the same magnitude. These embodiments are beneficial,for example, where the first and second sets of loads 132, 134 bothoperate at the same voltage.

In other embodiments, the split bus regulator 118 is configured so thatthe second regulated DC voltage 122 and the third regulated DC voltage124 have different voltages. These embodiments are beneficial, forexample, where the first set of loads 132 operates at one voltage andthe second set of loads 132 operates at another voltage.

In many embodiments, the split bus regulator 118 is configured to applya voltage between the first output 108 and the third output 112 that issubstantially the same (e.g., 380 Vdc) as the DC source voltage 120. Insome instances the voltage applied to the first 108 and third output 112is low enough so that the three conductors 126, 128, 130 may beassembled in close proximity (e.g., in a single cable and/or singlepiece of conduit) to feed power to the N loads, which may be locatedremotely from the DC power supply 104.

In other embodiments, however, the split bus regulator 118 may apply avoltage between the first output 108 and the third output 112 thatrequires the first and second outer conductors 126, 130 to be physicallyseparated so as to conform with electrical codes. Referring to FIG. 2,for example, shown is another embodiment in which a second output 210 isadapted to couple to separate conductors 236, 238 so that a first andsecond outer conductors 226, 230 may be separated to comply withelectrical codes. In this embodiment the voltage between the first andsecond outputs 208, 210 is applied to a first set of loads 232 with aseparate feed (e.g., cable and/or conduit) than the voltage applied to asecond set of loads 234 from the second and third outputs 210, 212.

As discussed further herein, in many embodiments, when the first set ofloads 132, 232 and the second set of loads 134, 234 are symmetrical, thesplit bus regulator 118 operates at a very efficient state and most ofthe energy losses of the DC power supply 104 are due to losses from therectifier 116. And in several implementations, the potential of thecenter conductor 128, 228 is at, or very near, ground. As a consequence,the center conductor 128, 228 may be designated as a neutral line, whichdoes not require additional protective switch gear; thus saving asubstantial amount of money.

In many embodiments, when the first set of loads 132, 232 and the secondset of loads 134, 234 are asymmetrical, current may flow in the centerconductor 128, 228 in the direction of the split bus regulator 118 whileproviding power to both the first set of loads 132, 232 and the secondset of loads 134, 234.

The control module 114 in this embodiment is generally configured toenable control, via the I/O module 106, of the rectifier 116 and thesplit bus regulator 118. The control module 114 may be realized byhardware, software or a combination thereof, but it should be realizedthat the control module may be implemented by separate components andthat the rectifier 116 and the regulator 118 need not be coupledtogether by a common control structure. The I/O module 106 may berealized by one or more of a display, keyboard, pointing device, and/ortouch screen device.

Referring next to FIG. 3, shown is a block diagram 300 of an exemplaryembodiment of the split bus regulator 118 depicted in FIGS. 1 and 2. Asdepicted, in this embodiment there are a first and secondelectrically-controlled switches 302, 304 that are arranged in series sothat the series combination of the switches 302, 304 is disposed acrossa first outer conductor 306 and a second outer conductor 308. As shown,a center conductor 310 is coupled between the first and secondelectrically-controlled switches 302, 304 and includes an inductiveelement 312. In addition, a first capacitor 314 is coupled between thefirst outer conductor 306 and a center conductor 310 and a secondcapacitor 316 is coupled between the second outer conductor 308 and thecenter conductor 310. The first and second capacitors 314, 316 in theexemplary embodiment have the same value and each of the electronicallycontrolled switches 302, 304 are substantially identical so that thesplit bus regulator 300 is substantially symmetrical relative to thecenter conductor 310.

Each of the electrically-controlled switches 302, 304 depicted in FIG. 3are realized by the combination of an insulated gate bipolar transistor(IGBT) and a passive diode. But this is certainly not required, and inother embodiments one or more other switching devices may be utilized toimplement the switches 302, 304. In one embodiment for example, fieldeffect transistors (FETs) are utilized, and in another embodimentinsulated gate commutating thyristors (IGCTs) are utilized. It iscontemplated, however, that other switching devices may be utilized inother embodiments. It should be recognized that the diodes depicted inthe switches 302, 304 may be integrated so as to be contained in thesame package, but this is not required, and the diodes may be added as aseparate component to the switching element.

As shown, each of the switches 302, 304 is controllable with acorresponding input 318, 320 that connects with the control module 114depicted in FIG. 1. In operation, each of the switches 302, 304nominally operate at a fifty percent duty cycle. Although not required,in many embodiments the voltage of the center conductor 310 is fed backto the control module 114 and the control module 114 modulates the dutycycle of the switches 318, 320 by sending control signals to the inputlines 318, 320.

In general, the split bus regulator 300 is configured, responsive to aDC source voltage applied across the first and second outer conductors306, 308, to apply a second regulated DC voltage across a first output308 and a second output 310 and a third regulated DC voltage across thesecond output 310 and the third output 312 of the split bus regulator300. Both the second and third regulated voltages are less than the DCsource voltage. As a consequence, two reduced and regulated DC voltagesare produced without either employing a step-down transformer prior torectification or a bucking stage following rectification.

In the exemplary embodiment depicted in FIG. 3, if the load impedanceacross the first and second outputs 308, 310 is less than another loadplaced across the second and third outputs 310, 312, then current flowsinto the second output 310 and through the center conductor in thedirection of the switches 318, 320 while power is delivered to bothloads. If, however, the load impedance across the second and thirdoutputs 310, 312 is less than the load across the first and secondoutputs 308, 310, then current flows in the center conductor 310 awayfrom the switches 318, 320 in the direction of the second output 310while power is delivered to both loads; thus the split bus regulator 300may have bidirectional current flow within the center conductor 310while power is delivered to a load across the first and second outputs308, 310 and another load placed across the second and third outputs310, 312.

Referring next to FIG. 4, shown is a schematic diagram of anotherembodiment of the split bus regulator 118 depicted in FIGS. 1 and 2. Thesplit bus regulator 400 is similar to the split bus regulator 300depicted in FIG. 3 except the inductor 312 is replaced with a firstinductor 420 in a first outer conductor 406 and a second inductor 430 inthe second outer conductor 408.

Referring next to FIG. 5, shown is a schematic diagram of yet anotherembodiment of the split bus regulator 118 depicted in FIGS. 1 and 2. Asshown, in this embodiment a commutating inductor 502 is utilized toprovide soft switching to in order to increase the overall energyefficiency of the split bus regulator.

Referring next to FIG. 6, shown is an exemplary embodiment of amultiple-split-bus regulator 600. As shown, in this embodiment, themultiple-split-bus regulator 600 is capable of driving three loads.Although not required, the voltage across each load may be 300 Volts sothat the total voltage across Load 1, Load 2, and Load 3 is 900 Volts.Beneficially, this embodiment also provides 600 and 900 volts if needed.Additionally, one of ordinary skill, in light of this disclosure, willrecognize that alternative voltages may be generated and that thevoltages may be asymmetrical.

Referring to FIG. 7, shown is a flowchart depicting an exemplary methodin accord with the embodiments described with reference to FIGS. 1-6. Asshown, an alternating current is received (e.g., from the AC sourcevoltage 102)(Block 702) and is rectified to generate a direct currentvoltage (e.g., regulated DC voltage 120)(Block 704). The direct currentvoltage is then converted into at least two regulated DC voltages (e.g.,regulated DC voltages 122, 124)(Block 706).

As depicted in FIG. 7, a first of the at least two regulated DC voltages(e.g., regulated voltage 122) is applied across a first and a secondoutputs (e.g., the first and second outputs 108, 110) and a second ofthe at least two regulated voltages (e.g., regulated voltage 124) isapplied across the second and a third output (e.g., the second and thirdoutputs 110, 112)(Block 708). And when a first impedance (e.g., theimpedance of the first set of loads 132) across the first and secondoutputs is less than a second impedance (e.g., the impedance of thefirst set of loads 134) across the second and third outputs, current isreceived via the second output (e.g., the second output 110) while poweris delivered to the first and second impedances (e.g., the impedances ofthe first and second sets of loads 132, 134) (Block 710).

Those skilled in the art can readily recognize that numerous variationsand substitutions may be made in the invention, its use and itsconfiguration to achieve substantially the same results as achieved bythe embodiments described herein. Accordingly, there is no intention tolimit the invention to the disclosed exemplary forms. Many variations,modifications and alternative constructions fall within the scope andspirit of the disclosed invention as expressed in the claims.

1. An apparatus comprising: a rectifier configured to rectify analternating-current (AC) voltage so as to generate a firstdirect-current (DC) voltage; and a switch-mode regulator including afirst, second, and third outputs, the first and second outputsconfigured to connect to a first load and the second and third outputsconfigured to couple to a second load, wherein the regulator isconfigured to apply, using the first direct-current voltage, a regulatedsecond DC voltage between the first and the second outputs and aregulated third DC voltage between the second and third outputs, each ofthe regulated second and third DC voltages having a magnitude that isless than the magnitude of the first DC voltage; wherein the switch-moderegulator is configured to receive current from the second output, whileproviding power to the first and second loads, when an impedance of thefirst load is less than an impedance of the second load and theregulator is configured to send current out of the second output whenthe impedance of the second load is less than the impedance of the firstload.
 2. The apparatus of claim 1, wherein the rectifier is anactive-boost rectifier configured to generate the first direct-current(DC) voltage with a magnitude that exceeds the magnitude of a passivelyrectified DC voltage from the AC voltage.
 3. The apparatus of claim 1,wherein the second output of the regulator includes two connectors, afirst of the two connectors is adapted to connect to the first load andthe second of the two conductors is adapted to connect to the secondload so as to enable a voltage of the first output to be physicallyseparated from a voltage of the third output.
 4. The apparatus of claim1, wherein the regulator includes a feedback line connected to thesecond output to enable closed-loop regulation of the regulated secondand third voltages.
 5. The apparatus of claim 1, including a visualindicator configured to alert a user of a load imbalance between thefirst load and the second load.
 6. The apparatus of claim 1, wherein theregulator is configured to apply the regulated second DC voltage to thefirst and second outputs at the same magnitude as the regulated third DCvoltage, and wherein a voltage between the first and third outputs has amagnitude that is approximately the magnitude of the first DC voltage.7. The apparatus of claim 1, wherein the regulator includes a fourthoutput configured to connect to a third load, the regulator beingconfigured to provide a regulated fourth voltage between the thirdoutput and the fourth output.
 8. A method for providing direct-currentpower, comprising: converting a direct current voltage into at least tworegulated DC voltages; applying a first of the at least two regulated DCvoltages across a first and second outputs and a second of the at leasttwo regulated DC voltages across the second output and a third output;and receiving, when a first impedance across the first and secondoutputs is less than a second impedance across the second and thirdoutputs, current via the second output while delivering power to thefirst and second impedances.
 9. The method of claim 8 including:receiving an alternating current; and rectifying the alternating currentto generate the direct current voltage.
 10. The method of claim 8,including: applying the voltage of the second output to a first andsecond conductors; and separately distributing the first and second ofthe at least two regulated DC voltages.
 11. The method of claim 8,wherein converting includes converting the direct current voltage intothree regulated DC voltages, and applying includes applying a third ofthe three regulated DC voltages across the third output and a fourthoutput.
 12. The method of claim 8, wherein the voltage across the firstand third outputs is substantially the same voltage as the directcurrent voltage.
 13. The method of claim 8, wherein the convertingincludes dividing the direct current voltage and switch-regulating thedivided voltage.
 14. The method of claim 8 including modulating the atleast two regulated DC voltages in response to feedback from at leastone of the outputs.
 15. An apparatus comprising: a first and secondouter conductors adapted to enable a direct current voltage to beapplied across the first and second outer conductors; a first and secondelectrically-controlled switches, the first and secondelectrically-controlled switches arranged in series to form a seriescombination, the series combination of the electrically-controlledswitches disposed between the first and second outer conductors; acenter conductor coupled between the a first and secondelectrically-controlled switches, the first electrically-controlledswitch regulating a second DC voltage that is applied between the firstouter conductor and the center conductor, and the secondelectrically-controlled switch regulating a third DC voltage that isapplied between the second outer conductor and the center conductor,wherein during operation, power is delivered, irrespective of thedirection of current flow in the center conductor, to both a first loadcoupled between the first outer conductor and the center conductor and asecond load coupled between the second outer conductor and the centerconductor.
 16. The apparatus of claim 15, wherein the center conductorincludes an inductor configured to filter the voltage of the centerconductor.
 17. The apparatus of claim 15, wherein the first outerconductor includes a first inductor and the second outer conductorincludes a second inductor.
 18. The apparatus of claim 15, including afirst capacitor coupled between the first outer conductor and the centerconductor and a second capacitor coupled between the second outerconductor and the center conductor.
 19. The apparatus of claim 15,wherein each of the first and second electrically-controlled switchesincludes a switch device selected from the group consisting of aninsulated gate bipolar transistor (IGBT), a field effect transistor(FET), gate turn off devices; IGCT insulated gate commutatingthyristors.